Generally, a capacitive microphone utilizes a capacitance between a pair of electrodes which are facing each other to generate an acoustic signal. A MEMS microphone may be manufactured by a semiconductor MEMS process to have an ultra-small size.
The MEMS microphone may include a substrate including a cavity, a bendable diaphragm and a back plate which is facing the diaphragm. The diaphragm can be a membrane structure to generate a displacement due to the acoustic pressure. In particular, when the acoustic pressure is applied to the diaphragm, the diaphragm may be bent toward the back plate due to the acoustic pressure. The displacement of the diaphragm can be sensed through a change of capacitance between the diaphragm and the back plate. As a result, an acoustic wave can be converted into an electrical signal for output.